Abstract: This paper introduces the concept and definition of inherent safety design and emphasizes its important role in the engineering design of petrochemical plants. The safety protection layers in industrial processes and the position of instrumentation control in the layers are discussed. BPCS and SIS have different functions for their different realization modes and response time. According to the characteristics of BPCS and SIS, the fail-safe principle and separate setting principle for instrumentation control in inherent safety design are presented. Based on engineering design experiences, the typical practice of instrumentation control in inherent safety design is put forward to reduce the material reserves, prevent the further leakage of chemicals and maximize the application of SIS system.

Key words: inherent safety design, safety protection layer, instrumentation control, EBV valve, BPCS system, SIS system